A variety of exterior wall systems are used in the construction industry. For example, an exterior insulation and finish system (EIFS) is one such exterior wall system. A typical EIFS construction is shown in cross-section in FIG. 1 where a portion of a structure's framing and foundation are shown with the EIFS built thereon. More specifically, in terms of residential construction, foundation 10 is typically a cinderblock or cement foundation having a wood sill plate 12 bolted thereon with wood (or metal) framing studs 14 attached to and extending up from sill plate 12. The conventional EIFS wall system starts with sheathing 16 (e.g., plywood, oriented strand board, cement board, gypsum board, etc.) attached to studs 14 and wrapped with a building wrap material 18 (e.g., felt or other vapor barrier type of building wrap) that is impervious to moisture and wind. Insulating sheathing 20 (e.g., expanded polystyrene or other synthetic insulating boards) are then bonded or glued directly to building wrap material 18 and one or more coats of a (synthetic stucco) finish 22 are applied onto insulating sheathing 20.
While finish 22 is generally designed to be impervious to water, terminations in the wall system around windows and doors have traditionally been the source of moisture entry. The use of building wrap material 18 is generally required by code to prevent moisture from passing therethrough into the structure. However, with nowhere to go, the moisture eventually migrates behind building wrap material 18 into sheathing 16 and even studs 14. Then, building wrap material 18 tends to trap the leaked-in moisture thereby causing moisture damage that can only be repaired by the costly repair/replacement of the EIFS system and, possibly, framing studs 14. Numerous other exterior wall systems such as direct exterior finish systems (DEFS) can also suffer from trapped moisture problems.
One approach to solving this problem involves the use of a lath or other water management system (not shown) interposed between building wrap material 18 and insulating sheathing 20. However, none of the prior art solve the problem of what to do with the moisture if or once it reaches the lower portion of the EIFS.